Color photography



COLDR'. PHOTOGRAPHY Filed Jury 1922 :maya fein yelaz'ne univa/led Patented Feb. 10, 1.925.

UNITED *STATES PATENT OFFICE.

JOHN G. CAPSTAFF, OF ROCHSTER, NEW YORK, ASSGNOR TO EASTMAN KO'DAK COM- PANY, F ROCHESTER, NEW YORK,

COLOR PHOTOGRAPHY.

.A CORPORATION or NEW YORK.

Application ledJuly 12, 1922. Serial No. 574,364.

To all whom it may concern.:

Be it known that I, JOHN G. CAPSTAFF, a subject of the King of Great Britain, residing at Rochester, in 5 roe and State of New certain new and useful Improvements in Color Photography, of which the following a-full, clear, and exact specification.

This inventionrelates to color photography and particularly to that method of making color reproductions that comprises forming in registry upon opposite surfaces of a transparent support two imagesin complementary colors. i

One of the methods by which color images have been made is b forming relief images in a colloid, dyemg these, andv then superposing the dyed images. These relief images have been made byhardening or tanning the colloid in accordance with' a photographic image and washing ofl:l the unaffected colloid. Inasmuchas the hardened or tanned portion is that part facing. the printing light, it has been necessary either tO transfer the affected colloid layer, and .wash olf what had been'th'e lower portion; or to print through a transparent support and wash off the upper layer. Either method was 'inapplicable to the formation of a relief image in emulsions already coated on the opposite surfaces `of a transparent support. I have discovered a method by which the wash-olf Vprocess may be applied to such coatings so that the lower portions next the support will be `tanned or hardened, leaving the upper portions relatively unaffectedv and capable of being'washed off. This method is further applicablezto the making of-single reports.

In order to make the steps of my process clearer reference will be made-to the accompanying drawings, all of which'arc in section and-'on a much enlarged scale and inwhich the same reference characters .are used throughout to designate the same part.

Fig. l "shows a negative silver image .formed in each coating by a non-tanning developer;

v Fig. 2 shows in addition to the orlgmal the county of Mon' York, have invented` lief images on transparent or opaque sup-` negative silver image, a silver positive image formed in the same coating by a tanning developer;

Fig. lshows the relief left by washing oft'the untanned portions;

Fig. 4 shows the bleached relief images;

Fig. 5 shows the dyed relief images; and

F ig: 6 shows a single relief image on an Opaque support.

pon a transparent support 1 such as motion picture film, with sensitive photo graphic gelatino-bromide emulsion coatings 2 and 3 upon the opposite surfaces,` there are formed registering silver images 4 and 5. The light images are printed or projected thereon by `any known methods, one image being the result of van exposure of the desired subject through a red lter and the other being the result of an exposure through a green filter. The'silver images shown are then developed by the use of at developer such as 'monomethyl paramidophenol-sulfate which does not have any appreciable action in the way of hardening or tanning the gelatine emulsion. After washing, but without fixing, the emulsions are exposed to light, thus rendering developable all the undeveloped grains of silver salt, lafter which the lilm is submitted toI a developer, Such as pyro, having a strong tanning action on the gelatine in the vicinity of the grains being developed. There are thus formed silver images 6 and 7 in the lower portions of the layers .2 and 3, these images being in a mass of differentially tanned or hardened gelatine, and being the inverseof the images 4 and 5. If, as I prefer, the images .4 and 5are negatives, the corresponding images 6 and f7 will be positives. At this period the film if eX- amined will appear to be of uniform heavy density, It is then submitted to warm water and the still soluble outer portions dyed with colors, complementary to eachface and a red dyed relief image 11 on the other surface.

I do not adhere to any particular formulae for the developing and reducing baths as these'aiewell known. It is necessary only that the first developing bath have the minimum tanning action and the second have great tanning action. For the sake of completeness I will mention as satisfactory examples'of the baths the following: First' developin0r bath:

Monomethy p a r amidophenol-sulfate 20 grams Sodium sulfite 195 Potassium bromide-- 2.5 Potassium carbonate Water 3000 cc. Second developing bath:

Pyrogallic acid grams Sodium sulte 440 Sodium carbonate 440 4Water 1000 cc. Reducing bath:

Potassium permanganate 2 grams Sulphuric acid 10 cc. Water 1000 The utilized properties .of the baths are, in themselves, well known, and many equivalent baths might be mentioned.

The 'advantages of this process are obvious. It permits the printin of the image from the front of each em sionand avoids any transfer or registration of layers containing images. It -is to be understood that when the support is spoken of as transparent, I mean that at the finish of the process it will transmit such li ht as is desirable or neces-V sary with the co ored imagesto give the desired effect.

It is to be understood that, While I have shown the process applied to a two-color process, the invention extends also to the method of formation of the individual :mage whatever the nature of the sup ort on which the sensitive layer is carried. possible thus tol make a wash off image directly on its permanent support without exposure through its support. Fig. 6 shows such an image 12 on an opaque support 13, such aspaper, the steps necessary to make such a single image being analogous to those already described.

-It is not always necessary to expose to light before the second develo ment if the developer is` of such high re ucing power that 1t will act on the silver bromide, whether exposed or not. Such dev lo ers as caustic-pyro, without bromide, pr

uce',

mitting the layer to a bath that will develop the hitherto undeveloped portions thereof and render insoluble the portions' of the colloid immediately adjacent the newly develo ed grains and then washing loff the' solu le gelatine.

2. The process of making a photographic relief image that comprises exposing on its front surface a colloid layer containing sensitive silver salts and carried by a ysupport to a light image, submittin thegexposed layer on its support to a eveloper that support to a develo er that forms' a silver image therein and dlerentially tans thef colloid, washing olf thefuntanned colloid: leaving 'a relief images on itsoriginal support.

3. The process'of'jmakmg a colored image that comprises exposnga colloid layer containing a sensitive 'silver-salt to light, `Yide- 4forms asilver image therein without affect-,- ing the colloid, submitting the layer on its veloping in said layer a silver imageby the agency of a developer that does notA renderV the colloid insolub e, and .developing the hitherto undeveloped portions by the agency of a devel'o r that renders the elatine 1nsoluble, was n 0E the solublege atine, thus leaving a relie image and dyeing the relief image.

4. of making a colored image .that comprises exposing a colloid laer containing a sensitive silver"l salt to ght so -controlled as to render a part of said salt developable, developing a silver image by the agency `of a developer that d oes not render the colloid insoluble, and developing the rest of the salt to silver, by the agency of a developer .that renders the colloid insoluble in the immediate vicinity of the grains developed thereby, washing off the soluble gelatine, thusv leaving a relief image, re-

moving the `s'ilver from the relief image and dyeing the relief image. A

5. In eolor'photogra hyfthe method of making two-co or recor in registry in layers containing sensitive silver salts on opposite surfaces of a'support that comprises the formation of silver images in each layer by exposure and development in a non-tanning developer, and a second development in a, tanning developer, the removal of the untanned portions of the layers, the removal of the silver from the layers, and the dyeing of the layers..

6. In color photography thev method of making two-color records 1n registry in colloid layers containing sensitive silver salts lon opposite surfaces of a support that commaking two-color records in registry in colloid layers containing sensitive silver salts on opposite surfaces of a transparent support that comprises exposing the layers to light corresponding to different color aspects of a subject, submitting them to a developer thatforms silver images therein without aiectin .the colloid, and submitting them to a eveloper that forms silver images therein and tans the colloid differentially, washin o the unaected colloid, thus leaving re ief images, removing the silver therefrom and dyeingthe relief images in colors complementary to each other and to the light by which the corresponding images were first'produced. Y

Slgned at Rochester, New,York, this 8th day of'July 1922. e

JOHN G. CAPSTAFF. 

